The Piper J-3 Cub was the most popular commercial aircraft of the 1930's. Barely seven yards long and instantly recognizable in its yellow-and-black paint scheme, this nostalgic favorite became the foremost trainer of the era, eventually training 80% of the United States military pilots by the end of World War II. A new Cub was rolling off the assembly line nearly every 20 minutes, and many of these beloved airplanes are still around today.